A spectrometer is an analytical instrument used to determine the chemical content of a sample by irradiating the sample with a particular frequency or a particular band of frequencies of electromagnetic radiation and then analyzing the spectrum of the electromagnetic radiation from the sample. Since most chemical substances have their own distinctive and unique spectrum, a spectrum of a sample can be used to determine the chemical content of the sample. Many different techniques are used for such analysis, including external or internal reflection of the light beam through the sample, attenuation total reflection (ATR), transmission, diffuse reflection, grazing incidence, and reflection-absorption.
In conventional spectrometers, the sample to be analyzed is mounted on to a sample holder which is then placed on an accessory. The accessory, in turn, is mounted into the sample compartment of the spectrometer where the accessory and the sample must be properly aligned in the path of the beam of electromagnetic radiation used in the analysis. To analyze a second sample, the first sample is removed, the second sample is mounted on the accessory, and the second sample and the accessory is aligned. If a different accessory is required for the second sample, such as when solid and liquid samples are analyzed, additionally the new accessory must also be properly aligned.
U.S. Pat. No. 5,557,544, discloses a spectrometer including a central computer, and exchangeable components for the spectrometer, such as a radiation source, a detector, a beam splitter, a filter, and measurement probes. Each component has a data carrier for storing data identifying parameters specific to that component, such as the history and/or current properties of the component such as operation time, performance deterioration parameters, and calibration curves. The data carrier is readable and updatable by the central computer when the respective component is installed on the spectrometer. Although this device overcomes the problem of having to recalibrate the spectrometer each time a component is replaced, precise manual alignment of the sample and sample holder is still required before the analysis of the sample can begin.
U.S. Pat. No. 5,638,171 discloses a spectrophotometer which includes a sample compartment for receiving an interchangeable accessory. Each accessory includes rails which engage guides in the sample compartment of the spectrophotometer to assure that the accessory is properly aligned when fully inserted. Springs are used to resiliently hold the accessory in place. In addition, a latch is movable between a locked and an unlocked position to lock the accessory into position. Each accessory also includes an electric connection for connecting the accessory to the spectrophotometer. The electronic connection identifies the type of accessory being used. Sample cells are held within the accessory by being mounted on a sample cell holders which are held in place in the accessory by a screw. A carousel, having multiple sample cell holders, can also be mounted in the accessory. Although this device includes an electronic connection, making the setting of parameters on the spectroscope easier, in addition to mounting the sample module the user of the spectrophotometer must also lock the sample module in place to assure proper alignment of the sample module during testing.